Polarization-dependent oxygen, vacancy distribution in ferroelectric Hf0.5 Zr0.5 O2 capacitors
Résumé
The discovery of ferroelectricity in hafnia-based thin films has paved the way for their integration into non-volatile memory technologies, offering compatibility with CMOS processes and the potential for aggressive scaling. One significant aspect impacting the reliability and performance of ferroelectric Hf0.5Zr0.5O2 (HZO) capacitors is the oxygen vacancy (VO) concentration, which influences endurance, retention, and polarization stability. This study investigates the VO concentration profile for the woken-up state (10 4 cycles) in HZO-based ferroelectric capacitors (FeCAPs) in different polarization states (P ↑ and P ↓ ). The VO distribution is quantified using Hard X-ray photoemission spectroscopy (HAXPES), using incident photon energies from 3 to 9 keV to calculate the VO concentration profile across the HZO layer non-destructively. Results indicate that VO accumulates near the top TiN/HZO interface for the P ↓ state, while they drift toward the bottom HZO/TiN interface for the P ↑ state under the effect of the internal polarization field. This polarization-dependent VO distribution correlates with voltage and field offsets observed in electrical measurements, providing insights into defect mobility that can inform FeRAM device optimization. Our results show that the polarization behavior, i.e. the alignment and stability of electric dipoles within the HZO layer, strongly correlates with the distribution of VO, which plays a crucial role in enhancing the reliability and performance of ferroelectric memory devices. These findings enhance our understanding of the coupling between defect chemistry and ferroelectric properties in HZO, supporting the engineering of high-performance, CMOS-compatible ferroelectric memory technologies
Domaines
Physique [physics]
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Polarization-Dependent_Oxygen_Vacancy_Distribution_in_Ferroelectric_Hf0.5_Zr0.5_O2_Capacitors.pdf (515.56 Ko)
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